The PRI's Enrique Pena Nieto is perceived as the insurmountable favorite to become Mexico's next president this year. But a series of blunders have caused some to question his mettle as a candidate.

First, he struggled to name a single book he'd read, except for "parts" of the Bible. Then he couldn't quote the minimum wage nor the price of the omnipresent tortilla.

The man who would be the next president of Mexico, Enrique Pena Nieto, is not off to a good start.

For months, the election of Pena Nieto had taken on an air of near-inevitability. The handsome politician with the TV star wife consistently leads polls by seemingly insurmountable margins.

But with the campaign now taking shape in earnest, Pena Nieto has stumbled badly in a series of embarrassing, well-publicized gaffes that raise questions about his mettle as a candidate.

Mexicans will vote in July to replace President Felipe Calderon, whose six-year term has been plagued by violence and drug cartel warfare that have left as many as 50,000 people dead. Many voters are looking for a change. Calderon is barred by law from seeking reelection.

Pena Nieto's Institutional Revolutionary Party, or PRI, which ruled Mexico with an iron fist for seven decades until being unseated from the presidency in 2000, has positioned itself to return to power. Maintaining that it has reformed from its corrupt ways, the PRI has won several governorships and legislative offices to rebuild a formidable party machinery and push laws favoring its election bid.

Leading that bid is Pena Nieto, until September the governor of Mexico state, the nation's most populous. With other parties divided, smarting or in disarray, Pena Nieto has seemed unbeatable, his youthful appeal meant to target a new generation of voters with little memory of the PRI's dark past.

But amid his stumbles, Pena Nieto has shown no ability to improvise and muster a quick comeback to rescue himself.

His troubles started in early December at the renowned International Book Fair in Guadalajara, where he was presenting his own book, "Mexico: The Great Hope."

Asked to name three books that had influenced him, the candidate hesitated, stammered and looked to aides for help. Struggling, he eventually said he had read "parts of" the Bible. Then he named a Mexican work of fiction from the last decade, "La Silla del Aguila" (The Eagle's Throne), but got the author wrong. He attributed it to a leading historian, Enrique Krauze, but it was written by Mexico's most famous living novelist, Carlos Fuentes.

"What happens is when I read books, the titles don't always stick," Pena Nieto said by way of explanation.

The flub went viral, and Pena Nieto quickly became the butt of many a joke among rivals, on social networks and in the media. It seemed to confirm a widely held notion of the candidate as pretty but shallow. Some called it his "Oops moment," alluding to U.S. Republican presidential candidate Rick Perry's inability to remember which three government agencies he would close.

It was Fuentes himself who perhaps delivered the most bruising criticism.

"This gentleman has the right not to read me," Fuentes told the BBC Spanish-language service. "What he does not have the right to is to be president of Mexico, based on ignorance."

Pena Nieto later tried to make amends, explaining in Twitter messages that he felt embarrassed but was so busy with politics he didn't have a lot of time to read.

His case was not helped by his teenage daughter Paulina, who re-tweeted a message that criticized "a bunch of jerks who are part of the prole [proletariat] and only criticize those they envy." Prole is a derogatory term referring to poor people. The snobbish tinge of the missive did not go over well in a country with such an enormous class divide. (She too later apologized.)

The candidate's next faux pas came during an interview with the Spanish newspaper El Pais, when he could not say how much the minimum wage was. Nor could he quote the price of a kilo of tortillas, a staple in all Mexican working- and middle-class households.

Pena Nieto compounded his misstep, stating that he couldn't be expected to know the price of tortillas because "I am not the lady of the house," a comment seen as sexist and doubly insensitive.

Although these fumbles are unlikely to substantially erode his support, they do suggest that Pena Nieto is not the picture-perfect candidate that many here have thought him to be. It suggests that the PRI, on an uphill crusade to improve its image, also has work cut out for it in sustaining his candidacy.

"If today, when the competition still isn't real, he already has a black spot on his image, what can we expect when his adversaries unleash their strategies … and the real war starts?" Raymundo Riva Palacio, newspaper editor and political commentator, asked in a column titled "Would you vote for Pena Nieto?"

"This reinforces the collective impression that he is a little media figure for whom years of careful choreography on a controlled stage allowed the construction of an attractive image for voters."